The Larger Pacific Striped Octopus was only discovered in the 1970s, and is so rare it doesn't have a proper scientific name.

Photo: Dr. Roy Caldwell

The Larger Pacific Striped Octopus was only discovered in the...

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Richard Ross, a California Academy of Sciences senior biologist, breeds the octopus in aquarium tanks at his home.

Photo: Sean Havey, The Chronicle

Richard Ross, a California Academy of Sciences senior biologist,...

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Larger Pacific Octopuses mate dangerously ‘beak to beak' .

Photo: Richard Ross

Larger Pacific Octopuses mate dangerously ‘beak to beak' .

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Larger Pacific Striped Octopus showing stripes and spots.

Photo: Richard Ross

Larger Pacific Striped Octopus showing stripes and spots.

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Richard Ross feeds a grass shrimp to one of his Greater Pacific Striped Octopuses in the aquarium room of his home in Alameda. Ross is a marine biologist at the California Academy of Sciences and has been raising Greater Pacific Striped Octopuses at his home in hopes of bringing them to the Academy to be put on display.

Photo: Sean Havey, The Chronicle

Richard Ross feeds a grass shrimp to one of his Greater Pacific...

Image 7 of 8

Richard Ross in the aquarium room of his home in Alameda. Ross is a marine biologist at the California Academy of Sciences and has been raising Greater Pacific Striped Octopuses at his home in hopes of bringing them to the Academy to be put on display.

Photo: Sean Havey, The Chronicle

Richard Ross in the aquarium room of his home in Alameda. Ross is a...

Inside a spare bedroom in Richard Ross' Alameda home sits a massive aquarium system that holds what might be a future exhibit at the California Academy of Sciences in Golden Gate Park.

Within the largest tank, the senior academy biologist is attempting to raise and mate a species of octopus so rare it hasn't yet been assigned a scientific name.

For now, they're called the Larger Pacific Striped Octopus - a name that belies their relatively small size.

The 100-gallon aquarium, which is among six in Ross' room, is the breeding ground for two females and three males, which measure between 8 and 10 inches from the tip of one of their eight arms to another. The animals' bodies, which are called their mantles, are about the size of apples.

With all the tanks, there is barely enough room to move around.

"But there's enough space for my daughter and her bed to move in if she wants to," Ross insists. "She's 10, and she's there a lot anyway because she feeds all the animals whenever I'm away."

The creatures were unknown to science until about 20 years ago, when a Panamanian biologist first described them in an unpublished report. He discovered them while diving off the coast of Nicaragua in the 1970s.

In Nicaragua, the cephalopods live along the coast at depths of more than 130 feet. They prefer areas near the mouths of rivers, where currents stir up sediments that make it difficult for divers to spot the octopuses, said marine biologist Roy Caldwell, a UC Berkeley professor of integrative biology who is breeding and studying the animals in his own laboratory along with Ross.

The two men hope to mount an expedition to study them in the wild, said Caldwell, who dives around the world to study aquatic evolution. Caldwell is raising six of the Larger Pacific Striped Octopuses at the Berkeley lab, and calls them "the most beautiful octopuses I have ever seen."

When Ross has mated and reared enough of his rare octopuses, he plans to move some - he can't yet say how many - into the Steinhart Aquarium at the California Academy of Sciences, "so the public can see those rare animals too," he said.

He's a breeder

Ross certainly has experience raising and breeding octopuses. For the last four years, he has been studying a smaller cousin of the "Larger" ones. These thumb-size octopuses are known scientifically as octopus chierchiae, or the Lesser Pacific Striped Octopus.

These animals lay large eggs three to six weeks after mating. When the eggs hatch, tiny, swimming octopuses emerge that are easy to feed with tiny prey-like shrimp and sand fleas, Ross said.

By contrast, the "Larger" octopuses are a mystery. Their eggs are tiny and hatch after 20 to 50 days. When they do, the offspring are so small they look like plankton lying on the bottom of the aquarium.

"The really hard part is feeding them, because we still don't know what they eat, and if we can crack that mystery, it will open up all kinds of doors to raising them," Ross said.

Now his rare "Larger" octopuses are living together - peaceably so far - in their own 100-gallon home, surrounded by five other tanks. In addition to the "Lesser" octopuses, Ross' other tanks display a colorful spectrum of the saltwater fishes loved by home aquarists, including clown fish, orange spotted file fish and banggai cardinal fishes.

Already, the scientists have observed differences between the habits of these octopuses and other, more-studied species of octopus.

Hanging out together

Many octopus species live solitary lives and get together only briefly to mate and die. These animals from Nicaragua are far more gregarious, Caldwell said.

"They can cohabitate in pairs, the females can lay clutches of eggs again and again, and they sometimes share the same den, while groups of them are reported to live in colonies of 40 or more individuals," he said.

"They are the only octopuses known to mate 'beak to beak' - a position that may be viewed as dangerous considering their cannibalistic nature," Caldwell said. It's dangerous for the males, he explained, because female cephalopods often devour their mates after mating.